The thesis is based on clinical research. Studies presented in the first part concentrate on the role of radiation therapy to reduce or to prevent (re)stenosis after percutaneous transluminal... Show moreThe thesis is based on clinical research. Studies presented in the first part concentrate on the role of radiation therapy to reduce or to prevent (re)stenosis after percutaneous transluminal angioplasty (PTA) and arteriovenous fistulas. After reviewing the concept, a multicenter study is reported in which the efficacy of endovascular brachytherapy (EBT) for prophylaxis of restenosis after femoropopliteal PTA is evaluated. Further, a randomised trial is discussed that assessed the presumed preventive effect of external beam radiation therapy on anastomotic intimal hyperplasia in prosthetic arteriovenous fistulas in patients with renal failure. The second part of this thesis focuses on stimulation of vascular growth in patients with severe limb ischemia who are without regular surgical or endovascular treatment options. After reviewing the concept, a clinical study evaluated feasibility and safety as well as efficacy of autologous cell therapy (bone marrow). The angiographic results of this study and hypotheses on the clinical usefulness of digital subtraction angiography in the assessment of the effects on possible inducement of collateral circulation after cell-based therapy are separately considered. In conclusion: The modest effect of vascular radiotherapy is too cumbersome for widespread clinical implementation. Cell therapy in vascular patients is promising. The mechanisms are not completely elucidated, but the ultimate success however will rest on its ability to demonstrate clinical efficacy. Show less